The invention relates more particularly to a motor vehicle disk brake of the type described and shown in French patent application no. FR-A1-3004500, which includes:                a brake disk that lies in a plane transverse to an axially oriented axis of rotation of the disk;        a support fixed relative to a chassis of the vehicle,        two brake shoes, interior and exterior, each of which includes a friction lining a transverse friction face of which cooperates with an associated braking track of the disk, each brake shoe being mounted to slide axially in the support between an active position in which the friction face bears against the associated annular track of the disk an inactive position in which the friction face is spaced axially from the associated annular track of the disk by a particular operating clearance;        means for elastically returning each brake shoe to its inactive position, which comprise a return spring disposed between the brake shoe and the fixed support, for example.        
In a disk brake, the sliding of the brake shoes toward their active position is driven by a piston. The two brake shoes, interior and exterior, then clamp the disk strongly to slow down its rotation. The braking operation is therefore an active operation.
The brake shoes are pushed back toward their inactive position by the rotating disk. This is therefore a passive operation.
However, it can happen that the disk does not push the brake shoes back with sufficient force to separate them from the disk by a sufficient distance. For example, this can occur if the sliding of the brake shoes is of insufficient quality or even jammed, or if the design of the shoe itself creates “restitution”.
Although the brake shoes are no longer clamped actively against the disk, each of the annular tracks of the latter nevertheless rubs at all times against the friction lining carried by the associated brake shoe. The friction linings are therefore subjected to premature nonfunctional wear.
Moreover, this permanent friction is liable to cause heating that is harmful for some members of the disk brake.
This permanent friction also generates a residual torque that opposes the rotation of the disk. This increases the fuel consumption of the vehicle as well as degrading the performance of the vehicle.
To solve these problems of wear and heating, the aforementioned document proposes a disk brake in which, for each of the two shoes, there are two matched return springs, each of which includes means for compensating wear play of the friction lining of the brake shoe that deform plastically if the travel of the brake shoe to its active position is greater than said particular operating clearance.
To this end, a return spring includes at least one axially oriented section that is elastically deformable in traction between a rest state and a state of maximum elongation the value of which is equal to the particular operating clearance, the spring including at least one section deformable plastically by an axial traction force, forming said wear play compensating means, this plastically deformable section being conformed so as to be stretched plastically if the travel of the brake shoe to its active position is greater than the particular operating clearance.
The document WO-A1-027526 describes and shows one design of a brake shoe return spring.
The invention aims to improve the design and the performance of such return springs.
In such a brake in which each of the interior and exterior brake shoes is equipped with a pair of return springs, there may sometimes be encountered problems with balancing the sliding brake caliper relative to the disk, a brake shoe pressed against the disk possibly causing some residual torque.
Moreover, when acted on by the return springs with which it is equipped, it may also in some cases be found that the interior brake shoe—with which the front face of the brake piston cooperates—causes axial depression of the piston in its bore. It is therefore necessary to use return springs with different mechanical characteristics (load and stiffness) for the exterior and interior brake shoes.
The invention aims to remedy these disadvantages by proposing a new design of the return spring means of a sliding caliper disk brake, notably of the exterior brake shoe.